Microbiology and Biochemistry of Soil Organic Matter,Carbon Sequestration and Soil Health

摘要

Soil degradation is a major concern and leads to poor productivity,low soil organic matter,and diminished soil biodiversity resulting in impaired soil health.Microorganisms not only break down the added organic materials but are also the principal agents for the formation of mixture of organic molecules that constitutes soil organic matter(SOM).The biochemistry of soil organic matter,its formation and stabilization is reviewed.Decomposition of added crop residues in Vertisols was hastened by inoculation of a mixed microbial consortium(Arthrobacter,Streptomyces and Lysinibacillus)which promoted carbon mineralization,soil organic matter formation and improved the soil biological activity.Soil organic matter is well correlated to soil microbial biomass,soil biological activity and all other soil health indices.Results obtained by the authors showed that microbial inoculants have a high potential to induce carbon sequestration in soils when used as inoculants.High soil microbial activity indicates good soil health and long-term ability to sequester carbon.Good agricultural practices including integrated nutrient management improve microbial biomass formation and provide conditions for rapid turnover of organics by microorganisms,and higher accretion of SOM.Soil microbial biomass and SOM are thus two sides of the same coin and represent a continuum.The active fraction of SOM that is easily decomposable(labile C)is well correlated to microbial biomass.The soil organic matter content and labile C as a quantity parameter and soil respiration as an activity parameter give the best overall assessment of soil biological activity for routine use on dry soils in soil testing laboratories.In addition,measurement of soil protein and enzymes((3-glucosidase)yields useful additional information to assess management effects on soil health.